1. Field of the Invention
The present invention relates to a radio apparatus, a radio communication system, and a radio information notification method.
2. Description of the Related Art
Recently, there is widely adopted the protocol of a radio communication system that is called 3G (3rd generation).
There are some developmental stages also in this 3G. The cellular phone that adopts the protocol that is called 3.5G or HSDPA in which the transmission rate is sped up further, as well as the original 3G that is adopted in FOMA and the like, has appeared, too. In addition, the protocol that is called Super 3G or 3.9G is examined now.
The protocol in the radio communication system of group of this 3G is divided into two or more layers, and layer 2 of those layers is composed of three sub-layers of MAC (Medium Access Control), RLC (Radio Link Control) and PDCP (Packet Date Convergence Protocol).
FIG. 1 is a construction view of a protocol.
Layer 1 is a layer that is called a physical layer, and the layer 1 is a part which takes charge of an actual communication.
Layer 2, which is the upper layer, is composed of three sub-layers of MAC, RLC and PDCP.
Here, the mass of one processing function arranged in one layer or one sub-layer is called entity (entity). The PDCP entity and the RLC entity correspond to each LCH (Logical Channel: logical channel) and exist by the number of LCH to be used, and perform transmitting-receiving of PDU (Protocol Data Unit) having a one-to-one correspondence. Here, in the PDCP entity, the processing such as the concealment of data is done in 3.9G (Super 3G), and in the RLC entity, the processing such as the control of retransmission of data is done.
Moreover, in the MAC entity, PDU that has been forwarded from each RLC entity through each LCH is integrated into one PDU, and the integrated PDU is forwarded through TRCH (Transport Channel) to the layer 1 that is the subordinate position layer.
At the receiving side, the MAC entity divides the PDU, which is transferred from the layer 1 through the TRCH, into one or two or more PDU, and transfers the divided individual PDU through individual LCH to individual RLC entity.
Incidentally, though layer 3 exists, too, the illustration and the explanation are omitted because it is irrelevant directly to the present invention described later.
Here, in individual PDU, the mechanism that information can be exchanged with the opposing side by giving not only the user data but also the control information necessary for the entity on the opposing side is being examined by 3GPP (3rd Generation Partnership Project).
According to this examination, it is possible for individual entity of the transmission side to transmit the control information to the opposing entity of the receiving side. More in detail, for instance, when the PDCP entity of LCH#1 of PDCP sub-layer applies the control information to data and transfers the same to the RLC entity, the PDCP entity of LCH#1 on the receiving side can be operated in accordance with the control information referring to the control information. In a similar fashion to this, for instance, when the RLC entity of LCH#2 applies the control information to data and transfers the same to the MAC entity, the RLC entity of LCH#2 on the receiving side can be operated in accordance with the control information referring to the control information. As for the MAC entity, it is similar.
Here, it pays attention about the control information given by the MAC entity, and, in the following, it explains the control information given by the MAC entity.
FIG. 2 is a view showing data format of PDU including control information applied in the MAC entity. FIG. 2 shows only the RLC sub-layer and the MAC sub-layer at the transmission side.
The PDU shown in FIG. 2 has a data format in which SDU's, that are received from four RLC entities placed on the RLC sub-layers of four logical channels, are integrated, and header H and MAC control information are added. This PDU is transferred to the layer 1 so that the layer 1 transmits the PDU to the receiving side on a radio basis.
FIG. 3 is a figure where the data flow of the scene where the control information is given by the MAC entity is shown.
As mentioned above, in the MAC entity at the transmission side, SDU's of four RLC entities, which are placed on the RLC sub-layers at the transmission side, are integrated, and header H and control information CONT are added so that one PDU is created. The thus created PDU is transmitted. At the receiving side, the PDU is received so that the MAC entity at the receiving side removes the header H and the control information to be separated into SDU on individual LCH. The thus separated SDU is transferred to the associated RLC entity. The MAC entity at the receiving side operates in accordance with the removed control information.
FIG. 3 shows that the above-mentioned data flow is repeated for one communication. Incidentally, for the purpose of making it plainly here, it is shown that data is simply transmitted from one sending end to other receiving side. However, in an actual communication, the transmission and the reception are mutually complicated and it is repeated two or more times.
FIG. 4 is an explanatory view useful for understanding problems in the data flow explained in conjunction with FIG. 2 and FIG. 3.
PDU's of PDU#1, PDU#2, and PDU#3 are shown here. It is assumed that the first PDU#1 is normally received, the second PDU#2 fails in the reception due to the defect of the communication path for instance, and the third PDU#3 is normally received. It is assumed that the second PDU#2, which fails in the reception, is transmitted again later than the third PDU#3, and the PDU#2 that is retransmitted is normally received.
The MAC entity on the receiving side operates first in accordance with the control information on the PDU#1 at the time of the reception of PDU#1, and, next, does not perform operation according to the control information as for PDU#2 at that time because it failed in the reception, and operates in accordance with the control information on the PDU#3 at the time of the reception of the following PDU#3. And, in addition, it operates in accordance with the control information on PDU#2 that is sent again afterwards. That is, though the control information on PDU#3 is the latest control information originally, the receiving side MAC entity operates as if the control information on PDU#2 that is sent again is the latest, in the scene of FIG. 4, and there is a possibility that erroneous operation is performed.
For instance, assume that the sending end shown in FIG. 3 is a base station, and the receiving side is a cellular phone, and it is assumed that there is in PDU#1 transmitted from the base station to the cellular phone the control information directed to lower the volume of the data transmitted from the cellular phone to the base station because processing in the base station is crowded. Moreover, it is assumed that there is in PDU#2 transmitted the control information directed that it is acceptable to greatly raise the volume of the data to be transmitted from the cellular phone to the base station because processing in the base station becomes empty. In addition, it is assumed that there is in PDU#3 transmitted the control information directed that the volume of the data to be transmitted from the cellular phone to the base station is to be lowered greatly because processing in the base station is crowded again.
In this case, the cellular phone will be misunderstood with the one that it is possible to transmit by greatly raising volume of data to the base station because it is received delaying PDU#2 though the cellular phone will transmit data to the base station while greatly limiting volume of data after PDU#3 is received if PDU#3 is received back than PDU#2. In this case, the processing performance is exceeded for the base station, and the state that the data transmitted from the cellular phone cannot be processed might be caused.
Moreover, in a case where the control information on PDU#2 is a control signal which directs reset to return the receiving side to the initial state, PDU#2 is reset in accordance with the timing not originally intended, at which timing PDU#2 is sent again, and it is likely not to be communicated normally.